STEEL MANUFACTURE—ORE DOCKS
At the south shore of Lake Erie, the ore meets the coke from western Pennsylvania and coal from the Ohio coal-fields, and as a result new centres of iron and steel manufacture have grown up along this line of "least resistance." The ore is unloaded at the docks by means of mechanical scoops and shovels. So cheaply and quickly is it mined and transported that it is delivered to the smelteries at a cost varying from $1.75 to $3.25 per ton.
LAKE SUPERIOR IRON ORE FIELDS
There are three forms in which iron is used—cast iron, wrought iron, and steel. Cast iron is crystalline and brittle. The product as it comes from the blast furnace is called pig-iron. In making such commodities as stoves, and articles that do not require great strength, the pig-iron is again melted and cast into moulds which give them the required shape. Cast iron contains from one to five per cent. of carbon.
Wrought iron is malleable, ductile, and very flexible; when pure it is also very soft. It is prepared by melting pig-iron in furnaces having such a shape that the molten metal can be stirred or "puddled" in contact with the air. By this means the carbon is burnt out, and while still at a white heat the pasty iron is kneaded or "wrought," in order to expel other impurities.
Steel is a form of iron which is thought to contain a chemical compound of iron with carbon. It is stronger than iron and finer in grain. Formerly, steel was made by packing bars of pure iron in charcoal powder, the whole being enclosed in clay retorts that were heated to whiteness for about three days. The product obtained by this method is known as cementation steel. It is still used in the manufacture of cutlery, tools, and fine machinery; it is likewise very expensive. In smelting certain ores it is easy to burn out the carbon in open furnaces, and "open-hearth" steel is an important factor.